1. Field of the Invention
The invention relates to the field of absorbent garments in general, and more particularly to an elastic laminate that can be incorporated into absorbent garments to provide cloth-like elastic regions having improved fit and aesthetics.
2. Description of Related Art
Disposable absorbent garments such as infant diapers or training pants, adult incontinence products, and other such products are well-known in the art. Typically, the chassis of such garments comprises a liquid-permeable body-contacting liner sheet (or “topsheet”), a liquid-impermeable backing sheet (or “backsheet”) (collectively the “sheets”), and a moisture-absorbent core fiber (or “absorbent core”) that usually is made of a mat of randomly arrayed cellulose fiber and is generally disposed between the topsheet and the backsheet. These garments oftentimes incorporate elastic elements in the waist, stomach, and leg areas for improving the fit of the garment. The waist and stomach elastic elements increase the flexibility of the garment, allowing the same garment to accommodate a greater range of body sizes. In addition, they make the garment more form-fitting for the wearer. Leg gather elastic elements and standing leg gathers have also been employed to help reduce leakage of urinary and bowel movement (“BM”) from the garment when the absorbent cores cannot absorb body exudates fast enough. Leg gathers are known in the art, and U.S. Pat. No. 5,660,664 issued to Herrmann, the disclosure of which is incorporated by reference herein in its entirety, discloses an exemplary method of manufacturing leg gathers.
These garments typically are prepared by continuously supplying the various components of the garment, and forming these components into the final garment. The elastic elements are continuously supplied at several different points of the assembly process, and are coated with adhesive prior to bonding to the garment components.
Methods of bonding elastics to garment materials have been previously discussed in the art. An example of disposing elastic elements between layers of sheet material is given in U.S. Pat. No. 5,870,778 issued to Tharpe, the disclosure of which is incorporated by reference herein in its entirety. Tharpe discloses coating the garment materials with adhesive to affix the elastic elements therein. A common procedure for affixing elastic elements in the industry today is a spiral spray adhesive application as disclosed in U.S. Pat. No. 4,815,660, issued to Boger, the disclosure of which is incorporated by reference herein in its entirety. Spiral spray adhesive application consists of ejecting a bead of hot melt adhesive, directing jets of pressurized air to form an elongated adhesive fiber from the bead, and imparting a rotational motion to the adhesive fiber. The spirals of adhesive are then deposited on the target substrate, here elastic elements, which are then associated with the garment materials. In usage, the adhesive spray coats not only the elastic elements but also “oversprays” to other sites, causing a number of undesirable consequences.
First, the garment materials that are “oversprayed,” e.g., portions of the topsheet, the bottom sheet, and the absorbent core, become rigid upon hardening of the “oversprayed” adhesive making the garment less comfortable for its wearer. This has been referred to as the “plywood effect.” Second, the “overspray” coats parts of the assembly machinery that must then be periodically cleaned of the adhesive. Third, the elastic elements may not be uniformly coated with the adhesive due to the nature of the spraying operation, and therefore the elastic elements may not bond to the garment materials as well as if they had been more uniformly and completely coated with the adhesive. Finally, the “overspray” is wasted adhesive, increasing the cost of materials for the finished garment.
Previous attempts have been made to reduce the amount of excess adhesive that is applied to the garment, but these efforts have proved inadequate for reducing garment stiffening caused by the “plywood effect” and for reducing the cost of the garment due to excessive adhesive use. U.S. Pat. No. 5,993,433 issued to St. Louis et al., which is incorporated herein by reference in its entirety, discloses an adhesive pattern for applying adhesives to the gathers, but such adhesive patterns still contribute to excessive garment stiffness and cost. U.S. Pat. No. 6,235,137 issued to Van Eperen et al., which is incorporated herein by reference in its entirety, discloses a method of coating an elastic strand with a filament of adhesive, but this coating process is still subject to overspraying, and does not provide a complete coating of adhesive on the elastic.
Previous attempts to incorporate elastic materials into absorbent garments have also failed to simulate cloth-like materials, both with regard to aesthetic desirability and comfort and fit. For example, garments having spaced elastic strands, provide a heavily corrugated appearance and fit that allows the elastic strands to press against the wearer in such a way that comfort and fit are sacrificed. Other garments have replaced the elastic strands with an elastic film that simulates cloth materials in appearance and fit better than spaced elastic strands, but still fail to provide the desirable breathability characteristics of cloth, which are better provided by constructions having spaced-apart elastic strands. In still other garments, elastic strands have been sandwiched between nonwoven layers, but the layers have been bonded to one another by heat bonding or adhesives, causing the overall laminate structure to be rigid and uncomfortable to wear. The problems associated with these prior art constructions are particularly manifest in the waist-encircling side panels of absorbent garments, which define, in large part, the overall look and feel of absorbent garments.
Accordingly, there exists a need to provide an elastic laminate that can be incorporated into absorbent garments to provide a cloth-like look and feel, improved comfort and fit, and maintain the high breathability of spaced elastic strand constructions.